Supporting element for mounting heat exchanger for quenching thermally cracked gas

ABSTRACT

A SUPPORTING ELEMENT WHICH COMPRISES AT LEAST ONE ROLLER AND A ROLLER-BEARING FRAME AND IS USED TO SUPPORT A HORIZONTAL HEAT EXCHANGER FOR QUENCHING A THERMALLY CRACKED GAS IN SUCH A WAY THAT THE HEAT EXCHANGER CAN MOVE IN A HORIZONTAL DIRECTION IN ACCORDANCE WITH THERMAL EXPANSION. THE ELEMENT SI INSERTED BETWEEN EACH OF THE PROJECTIONS EQUIPPED ON BOTH SIDES OF THE SHELL OF THE HEAT EXCHANGER WITH THE BOTTOM OF THE SAID PROJECTIONS KETP AT APPROXIMATELY THE SAME LEVELWITH THAT OF THE CENTERLINE OF THE INLET OF THE HEAT EXCHANGER AND EACH CORRESPONDING SUPPORT TO THE PROJECTION FOR THAT PURPOSE.

United States Patent 1111 3,

[72] Inventors lchlro Tokumitsu [56] References Cited {321 ok so Asa UNITED STATES PATENTS lgf f fi 1,891,607 12/1932 Rainey 165/82 [21] PN 845,957 2,256,882 9/1941 Sebald l65/68X [221 Ned July 3 1969 2,285,651 6/1942 Fischer..." l65/82X [45] Patented June 28, 197] Primary Examiner- Frederick L. Matteson [73] Assignee ldemitsu Petrochemical Co., Ltd. Assistant ExaminerThe0phil W. Streule Tokyo, Japan Attorney- Fred C. Philpitt [32] Priority Aug. 17, I968 J p [31] 43/70497 [54] SUPPORTING ELEMENT FOR MOUNTING HEAT EXCHANGER FOR QUENCHING THERMALLY CRACKED GAS 1 Claim, 3 Drawing Figs.

[521 (LS. Cl 165/68 [511 Int. Cl F28f 9/00 [50] Field of Search 165/67, 68,

81, 82; 165/68, 69, 87, 91, 92; 263/(lnquired); 29/(lnquired) ABSTRACT: A supporting element which comprises at least one roller and a roller-bearing frame and is used to support a horizontal heat exchanger for quenching a thermally cracked gas in such a way that the heat exchanger can move in a horizontal direction in accordance with thermal expansion.

The element is inserted between each of the projections equipped on both sides of the shell of the heat exchanger with the bottom of the said projections kept at approximately the same level with that of the centerline of the inlet of the heat exchanger and each corresponding support to the projection for that purpose.

SUPPORTING ELEMENT FOR MOUNTING HEAT EXCHANGER FOR QUENCHING THERMALLY CRACKED GAS This invention relates to a supporting element for mounting a horizontal heat exchanger for quenching a thermally cracked gas on its support, and more particularly it relates to a supporting element comprising at least one roller and a rollerbearing frame, capable of moving the horizontal heat exchanger body in a horizontal direction in accordance with a thermal expansion of the connecting part of a thermal cracking furnace to the heat exchanger.

Generally speaking, the conventionally used heat exchanger for quenching the thermally cracked gas is not of horizontal type, but of vertical type from the viewpoint that the latter type can prevent such troubles as bending and damage due to the high temperature thermal expansion of the connecting part of the thermal cracking furnace. As the thermal cracking temperature for ethylene production by naphtha cracking is about 800 C., the connecting part is in a red-hot state, though it is made of heat-resistant special steel, and undergoes a considerable thermal expansion. Therefore, in such a case, it is convenient to hang a quenching heat exchanger vertically with its inlet adjusted to the outlet of the thermal cracking furnace by means of a supporting frame. Thus, when the connecting part consisting of a bent tube is thermally expanded in case of the vertical quenching heat exchanger, the said heat exchanger can swivel in accordance with the thermal expansion of the bent connecting part, and no trouble is brought about at the connecting part. However, in this case, the distance between the outlet of the thermal cracking furnace and the inlet of the said vertical heat exchanger is so long that the residence time of the thermally cracked gas within the connecting part is protracted. The thermally cracked gas leaving the thermal cracking furnace is chemically very unstable, and thus when the cracked gas is retained at a high temperature for a prolonged period of time, the secondary reaction takes place and the yields of the desired products are inevitably decreased. For this reason, it is desirable to rapidly quench the thermally cracked gas as soon as the gas leaves the thermal cracking furnace. Thus, the connecting part must be made as short as possible, and the horizontal quenching heat exchanger can only meet such a requirement. However, how to relieve the thermal expansion of the connecting part at such a high temperature is a problem in case of a horizontal heat exchanger.

The object of the present invention is to solve this problem.

The present invention consists in a supporting element comprising at least one roller and a roller-bearing frame, which is inserted between each of the projections equipped on both sides of a horizontal quenching heat exchanger for a thermal cracking furnace with the bottoms of the said projections kept at approximately the same level with that of the centerline of the inlet of the heat exchanger and each corresponding support to the projection to support the heat exchanger body in such a way that the heat exchanger body can move in a horizontal direction in accordance with thermal expansion of the connecting part of the thermal cracking furnace to the heat exchanger. i

That is to say, the thermal expansion in a horizontal direction of the connecting part can be relieved by rotation of the rollers of the supporting elements for mounting the heat exchanger, and the thermal expansion in the vertical direction never gives any stress to the heat exchanger, because the supporting elements for mounting the heat exchanger are so located that the tops of the supporting elements are held approximately on the same level as that of the centerline of the connecting part and that their level remains unchanged by thermal expansion of the connecting part in the vertical direction.

Further, the temperature of the connecting pipe at the outlet of the cracked gas of the heat exchanger as well as that of a cooling water conduit is considerably lower than that of the connecting part of athermal crackin furnace to the heat exchanger, and thus these pipes can su iclently withstand the stresses exerted by a slight movement of the heat exchanger.

The present invention will be explained in more detail with reference to the accompanying drawings.

FIG. 1 shows a side and cutaway view of one embodiment of the present invention employed in a heat exchanger for quenching the cracked gas.

FIG. 2 is a cross-sectional view of the heat exchanger with its accessories along the line AA perpendicular to the surface of FIG. 1.

FIG. 3 is a sketch of two rollers and a roller-bearing frame of the present invention.

Naphtha-cracked gas is produced within a heating pipe 2 in a cracking furnace l of FIG. 1, and led to an inlet 5 of a heat exchanger for quenching the cracked gas from the outlet 3 of the heating pipe 2 through a connecting part 4. The cracked gas quenched in a bundle of the cooling tubes 7 (refer to FIG. 2) in the heat exchanger of the cooling section 6 is withdrawn from the outlet 8 of the cracked gas of the heat exchanger. The heat exchanger is of shell-and-tube type, and high pressure water enters the inside of the shell from an inlet 9 connecting to a water conduit and leaves it from an outlet 10 as saturated steam after passing through the outside of a bundle of the cooling tubes 7 in the heat exchanger. The supporting system of the heat exchanger consists of the projections 14 equipped on both sides of the heat exchanger with the bottom of the projections at approximately the same level with that of the centerline of the inlet of the heat exchanger, of the supporting elements having two rollers 13 and a roller-bearing frame 11 (refer to FIG. 3), and of the supports 12 for fixing the supporting elements. The projections 14 attached on both sides of the heat exchanger are mounted on the rollers 13.

When the connecting part 4 thermally expands the heat exchanger with its projections 4 moves horizontally on the rollers 13 to relieve the stresses.

We claim:

1. in the known combination of a thermal hydrocarbon cracking furnace, a shell and tube heat exchanger for quenching the cracked gas products of said furnace, and a conduit between said furnace and said heat exchanger, the improvement which comprises an improved supporting system for said heat exchanger characterized by:

a. a plurality of spaced-apart projections located on the exterior shell of said heat exchanger;

b. said projections being located at approximately the same level with that of the centerline of the inlet of said heat exchanger;

c. a plurality of spaced-apart supports located beneath each of said projections; and

d. a roller positioned on each of said supports, each roller being mounted in a roller bearing frame, whereby said rollers support said spaced-apart projections in such a way that when the conduit between said furnace and heat exchanger expands and contracts, the heat exchanger will be free to accommodate such expansion and contraction by moving horizontally over said rollers toward and away from the furnace. 

